tire pressure question

[Del]

I just got a new tire (Bridgestone) for the front of my 650G.

The place I got it, Iron Pony, mounted and balanced it. When I picked it up, the fellow told me that it had 40 psi in it. When I told him that the owner's manual says to use 25 psi for regular riding and 28 for continuous high speed riding, he said that that was too low and that I should never run less than 36 psi.

I've been running 28 psi in the front for all the 14 years I've owned this bike with never a problem.

What are your thoughts?

Thanks,
Del

[vstan905]

Hah, I was just going to post a similar question. My GFs 81 GS650GL had new Metzlers put on and the front tire is at 36. Hope someone can help us here.

[DMPLATT]

You'll get different responses.

Some say this: The manual was written for tires of a different era and technology. Run the higher PSI.

I run 36 PSI.

Some say this: The bikes were designed to run at a certain pressure. Stick to the factory specs.



Well, I run 36 psi min. I've been doing this for almost a year and have not had any trouble. Actually, my bike grips and handles better at 36psi. I think it's the newer tire technology.

My .02

[Rico]

Well guys,
I'd say running 40lbs would help with your mpg. highway BUT It sure won't help with handling. When cornering you need that tire carcus to roll a bit and conform to the road.(not to much mind you) An over inflated tire
is much less forgiving and harder to regain control of after slipping.

Air presure is kinda like oil and tire likes and dislikes, people have opinions.

1000e with Spitfires

30 fr
32 r
Good even wear and good grip in all conditions.

Rico

[chuckycheese]

Me too

I totally agree with DMPLATT (Dave).

[dgeorge]

This is from Dunlops Motorcycle tire website
"As the world leader in motorcycle tires, Dunlop continues to be concerned about the lack of attention paid by many cyclists to proper use and maintenance of their tires, particularly when fitted to motorcycles intended for touring.

Dunlop technical personnel have attended touring rallies all over North America to collect vital data and give instructional seminars.

What we have observed at these rallies alarms us; many touring riders are not following proper tire maintenance procedures.

The requirements for proper tire usage are not complicated, but they do require consistent attention.

Owners and operators of motorcycles should closely monitor vehicle loadings to insure they are within the maximum loads and corresponding inflation pressures for their tires. This basic load and pressure information is clearly stamped on the tire sidewalls.

The tire does not support the load-the air pressure does. The manufacturer's ratings for the maximum load and inflation pressure are critical tire design elements. If not observed, the handling and performance of your motorcycle will be greatly affected.

We have checked inflation pressures at several touring rallies and found a high percentage of rear tires to be underinflated. In addition, weight checks of the rear axles of these motorcycles indicated a number of tires were loaded beyond maximum capacity.

Our inspections have not been limited to those cycles fitted with Dunlop tires; the situation exists for all brands of tires.

Regardless of the make of tire, this is a serious problem. Riders of motorcycles with significantly underinflated and overloaded tires will experience handling and steering difficulty. In addition, this abuse will result in disappointing premature tire wear and may cause catastrophic tire failure.

The addition of accessories, cargo, and dual riding to touring motorcycles aggravates the problems of overloading and underinflation. The excessive flexing that results from underinflation or overload causes buildup of internal heat, fatigue cracking and eventual carcass breakup resulting in complete failure. A consequence of such failure may be an accident with serious personal injury or death.

The appearance of stress cracks in the tread grooves is one indicator of overload and/or underinflation. If you find evidence of tread groove cracking, you should remove and replace the tire immediately. This damage is permanent and non-repairable.

Our inspection of tires of various style and manufacture at rallies and our subsequent testing have confirmed that underinflation (and/or excessive load) causes tread groove cracking and can result in more serious damage within the tire body. Uneven wear may also accompany underinflated use. Failure to heed these visual warnings can result in tire failure or blowout.

The use of trailers can also contribute to tire damage and touring motorcycle instability. Although most motorcycle manufacturers recommend against their use, a percentage of the motorcycles we have inspected were so equipped. The trailer tongue weight added to an already heavily laden motorcycle can fail a rear tire. The percentage of overloaded motorcycle rear tires found during our inspection would have been higher if trailer tongue weight had been considered. The forces of rapid acceleration and deceleration may also multiply the effects of trailer tongue weight.

To get the maximum safe use out of your tires and maximum touring enjoyment you should:
Properly maintain all aspects of your vehicle in accordance with manufacturer's recommendations. Read and reread your motorcycle owner's manual.
Never exceed the loading and accessories restrictions found in your motorcycle owner's manual, or the maximum load displayed on the tire sidewalls. Know your loaded vehicle weight!
Check air pressure at frequent, regular intervals, particularly just before and during long trips. Always use an accurate tire gauge* and check pressures only when the tires are cold (i.e., wait one hour after running). We have found many cheap gauges to be off more than 5 psi, so be sure to use a top quality gauge and preferably one that retains the pressure reading until reset!
Inspect your tires as often as possible. Look for irregular wear, any signs of cracking in the sidewalls and tread, blisters, knots, cuts or punctures. Immediately remove and replace damaged tires.
If in doubt, ask your motorcycle tire dealer to check your loading, inflation and tires. Remember, your tires stand between you and a serious accident.

For touring motorcycle loading, follow these general guidelines:
Light loads-single rider with some luggage (up to 200 lb. total)-minimum tire pressure of 32 psi front and 36 psi rear must be maintained.
Heavier loads-dual riding and/or luggage (from 200 lb. total up to maximum motorcycle capacity stated in the owner's manual)-pressure of 36 psi front and 40 psi rear must be maintained.
Please Note:
For any dual riding or fully loaded use, 40 psi must be maintained in all Dunlop rear tires fitted to touring motorcycles.

In addition to following these recommendations, notice what your tires are telling you while you're riding. If your steering response is slow or mushy, or if cornering and braking response is heavy, there's a good chance your tires are underinflated. Vibration or wobble may signal that actual tire damage has occurred and failure is imminent!

If you conscientiously follow our recommendations, you will enjoy better, longer, and safer tire performance and many, many miles of touring pleasure.

[Del]

Wow! Thanks for all the info, guys. That Dunlop piece is especially interesting.

I?ve always checked my tire pressure daily. If I?m riding, I checked the pressure that morning.

My old tire does have stress cracks in the grooves. I guess I?ll keep this one at 36 psi and see if it makes a difference.

Thanks again,
Del

[Bolder Biker]

Del,

I think that the answer is to go with the tire manufacturer's recommended tire pressure.

The Owner's manual for my 1983 GS750ES specifies a 28/32 psi front tire pressure for solo/passenger. This is what I have used for years for a variety of tires, mainly Metzeler ME33 Laser. However, the ME33 Laser has now been mostly replaced by the ME330, which has a 34 psi recommended pressure. The fact is that the tire has been designed to work optimally with a certain pressure, the tire manufacturers being the only people who know what this is.

BB

[KEITH KRAUSE]

That 25/28 stuff is ancient history. Maybe for the original IRC tires.
I run 36 fr/rr on my '79 1000.

[argonsagas]

Del, the lower pressures specified in the manual were for the tires available at the same time as the bike. They do not apply today.

As others have said, you need to go with the manufacturers specifications.

A couple of years ago I had an unexplained slow leak in my ME330 on rear of the GK. (This is unexplained because I could not find a problem, and it did not recur.)

Checked the tire Saturday morning, 38 psi cold. Back at home, I loaded it up and headed out in the afternoon.

It was almost entirely highway driving, but the next day the back end of the bike showed an occasional twitch on curves.

Not too worrisome if I was riding around the neighbourhood, but I was 1000 miles from home and travelling at 100mph when it first twitched. 8O

Off the road for a tire pressure check....34psi with my electronic gauge. But that was HOT pressure.

My portable pump...brand new the day before I left, failed. Finally found a gas station and refilled the tire. 42 psi at the warm temperature, and no problem after that. Tire never leaked again. (Never will, because it wore out, and has been replaced)

[Poot]

good info. I'm gonna have to put a wee more air in my tires. running at spec now.

[Jethro]

good info. I'm gonna have to put a wee more air in my tires. running at spec now.

Me too. I never thought about the fact that tire tech has changed and I always followed the pressure specs on the sticker on my rear fender.

[chuckycheese]

Great

Me too. I'm going to be more careful from now on. Thanks to Daniel for the comprehensive information.

[pidgey]

I have Bridgestone Spitfires on my 850, and I see that Bridgestone recommends following the motorcycle manufacturers recommended tire pressures. http://www.motorcycle-karttires.com